| 1. |
- Axelsson, Josefine, 1992-
(författare)
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Interglacial climates in proxies and models : Utilizing sampled oxygen isotopes and model simulations to understand past Indian summer monsoon variability
- 2024
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The study of Earth's climate system, including the mechanisms driving monsoon systems, is a key area of research within environmental sciences. Monsoons, vital for billions of people, are complex atmospheric phenomena influenced by various global factors, including orbital changes and natural climate variability. Among monsoon systems, the Indian summer Monsoon (ISM) is of particular interest due to its significant impact on the South Asian climate, agriculture, and water resources. Despite extensive study, comprehending the ISM's historical variability and its future implications remains a challenge. Utilizing natural archives like speleothems, along with stable water isotopes from precipitation and advanced climate model simulations, this thesis aims to decipher the ISM's responses to natural forcings across key interglacial periods—the Last Interglacial and the Holocene.Our findings indicate that the ISM's strength is critically influenced by slight variations in orbital configurations, leading to significant shifts in monsoon patterns. Our research also highlights the dual influence of local geographical features and distant atmospheric conditions on the ISM's annual variability. Most notably, we observed discrepancies between δ18O values obtained from isotope-enabled climate models and those derived from speleothems. This insight indicates that the models need refinement to accurately mirror the complexities observed in the proxy records and that the uncertainty parameter in speleothem records needs to be improved.The alignment between proxy and model data is crucial for a more accurate reconstruction of past climates and for enhancing the predictive capabilities of future monsoon behavior under changing climatic conditions. By advancing our knowledge of the ISM's past, we are better equipped to anticipate its future. To achieve that, this thesis stresses the importance of bridging the gap between proxy data insights and climate model simulations. This would not only enrich our historical climate knowledge but also inform future climate projections, highlighting the indispensable role of interdisciplinary research in climate science challenges.
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| 2. |
- Bennich, Therese, 1989-
(författare)
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The transition to a bio-based economy : Toward an integrated understanding
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The bio-based economy has gained increasing attention in societal and academic debates over the past two decades, and is argued to hold solutions to several pressing sustainability challenges. However, it is not yet clear if the high-reaching aspirations of the bio-based economy can be realized. The bio-based economy discourse has been criticized for being promissory, vague, and single-sector focused, thereby overlooking larger systemic impacts, trade-offs, and unintended consequences that may result from pursuing the goals of the bio-based economy. Against this background, this thesis aims to advance an integrated and systemic understanding of the transition to a bio-based economy and what it implies for sustainability. Sweden is used as an empirical case, where specific bio-based economy goals, as well as their interactions and sustainability outcomes, are examined. The focus is primarily on developments in the forestry, agriculture, and energy sectors. The analysis also seeks to identify how goals related to the bio-based economy are interconnected with goals promoted by parallel sustainability initiatives, specifically the 2030 Agenda and the associated Sustainable Development Goals (SDGs). Integration is achieved by using systems analysis tools and methods. Further, the weak and strong sustainability paradigms, and the opposing definitions of sustainability they provide, are used to assess the contribution of the bio-based economy to sustainability. The integrated analysis provides a detailed and operational conceptualization of transition pathways to a Swedish bio-based economy. The goals of the Swedish bio-based economy are divergent and broad-reaching, emphasizing that there is no general agreement on what the transition to a bio-based economy entails. The results point to multiple barriers that need to be addressed to realize the goals of the Swedish bio-based economy. Goal conflicts constitute one such barrier. These are found internal to as well as across the bio-based economy and the parallel 2030 Agenda. Additional hindrances include policy resistance, negative cross-sectoral spillovers, and patterns of path dependency. However, the results also highlight several opportunities for supporting the transition process in a Swedish context. These opportunities include the identification of goals and interventions with synergetic potential, which offer a basis for developing efficient implementation strategies with high systemic impact. There is also large potential to support cross-sectoral collaboration and learning, based on shared interests and challenges. Finally, the results emphasize the importance of better understanding and addressing perceptions about risk, conflict, legitimacy, and trust in the transition process.In terms of the overarching question of what the bio-based economy implies for sustainability, the results find that the bio-based economy has been contributing to developments that align primarily with weak sustainability. From the perspective of the strong sustainability paradigm, the prospects of the bio-based economy are less promising, potentially leading to outcomes that could worsen ongoing environmental and social issues. For the future, fundamental changes to the way the bio-based economy is conceptualized and implemented are needed for it to contribute to sustainability according to the notion of strong sustainability.
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| 3. |
- Berntell, Ellen, 1989-
(författare)
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Understanding West African Monsoon Variability : Insights from Paleoclimate Modelling of Past Warm Climates
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The Sahel, a water-vulnerable region in West Africa, relies heavily on rainfed agriculture. The region experienced pronounced droughts during the 20th Century, emphasising the socio-economic importance of understanding the drivers of the rainfall variability. However, future rainfall projections remain uncertain due to the complex nature of the West African Monsoon (WAM), which is influenced by internal climate variability, external forcing, and feedback processes. Limited observational records in West Africa and the need for longer time series further complicate the understanding of these drivers. This thesis uses paleoclimate modelling to investigate internal and external drivers of monsoon variability in West Africa across four distinct periods. Our study confirms that atmosphere-only model simulations can capture the observed multidecadal rainfall variability in the 20th Century, even though reanalyses struggle to reproduce the correct timing. Analysis of a last millennium simulation using the Earth System Model EC-Earth3 identified two drivers of multidecadal rainfall variability, accounting for 90% of the total co-variability between the West African rainfall and Atlantic sea surface temperatures (SSTs). This finding strengthens our understanding of SST-WAM relationships observed during the 20th Century. An ensemble of climate model simulations (PlioMIP2) shows that high CO2 levels and a different paleogeography during the mid-Pliocene Warm Period led to increased rainfall and a strengthened WAM. Our study emphasised vegetation's crucial role in enhancing the monsoon in past climates. However, simulations forced with prescribed vegetation only capture a one-directional forcing. A mid-Holocene simulation using an Earth System Model with dynamic vegetation revealed that vegetation feedbacks strengthen the WAM response to external orbital forcing but are insufficient to shift the monsoon northward or increase vegetation cover over the Sahara. These results reveal a dry bias and under-representation of simulated vegetation compared to proxy records, highlighting the importance of model development and the need for additional feedback processes in driving an enhanced, northward WAM and extending vegetation to the Sahara. Overall, this thesis advances our understanding of the drivers of West African monsoon variability and provides valuable insights for improving future rainfall projections in this vulnerable region.
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| 4. |
- Chakrawal, Arjun, 1992-
(författare)
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Novel approaches in modeling of soil carbon : Upscaling theories and energetics
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Soils contain more carbon (C) than terrestrial (above ground) and atmospheric carbon combined. Mismanagement of soil C could lead to increased greenhouse gas emissions, whereas practices leading to increased C storage would help mitigate climate change while improving soil fertility and ecological functions. At the center of these complex feedbacks, soil microorganisms play a pivotal role in the cycling of C and nutrients, and thus in soil-climate interactions. However, this role is not fully understood; therefore, developing new methods for studying their dynamics is essential for an understanding of bio-physicochemical processes leading to mineralization or stabilization of soil organic matter (SOM).Current soil C cycling models lack a robust upscaling approach that links SOM decomposition from process (μm) to observation scale (cm to km). Moreover, these models often neglect energy fluxes from microbial metabolism, which may provide additional constraints in model parameterization and alternative observable quantities such as heat dissipation rate to study decomposition processes. In this doctoral work, I investigated two aspects of microbial processes and their consequences for SOM dynamics: 1) use of energetics to constrain SOM dynamics by explicitly accounting for thermodynamics of microbial growth, and 2) spatial constraints at microscale resulting from the non-uniform distribution of microorganisms and substrates.In the first part of the thesis, I developed a general mass and energy balance framework for the uptake of added substrates and native SOM. This framework provided the theoretical underpinnings for understanding variations in the calorespirometric ratios—the ratio of rates of heat dissipation to CO2 production—a useful metric used as a proxy for microbial carbon-use efficiency (CUE). Moreover, in a follow-up work, I extended this mass-energy framework to describe dynamic (time-varying) conditions, which was used to interpret rates of heat and CO2 evolution from different soils amended with glucose. The dynamic mass-energy framework was also used as a tool for data-model integration and estimation of microbial functional traits, such as their CUE and maximum substrate uptake rates. In the second part of the thesis, I linked the micro and macroscale dynamics of decomposition using scale transition theory. The findings of this study were further validated from laboratory experiments, in which spatial heterogeneity in the added substrate was manipulated.Results from the first part show that the calorespirometric ratios can be used to identify active metabolic pathways and to estimate CUE. Further, the heat dissipation rate can be used as a reliable complement or alternative to mass fluxes such as respiration rates for estimating microbial traits and constraining model parameters. In the second part, I show that the co-location of microorganisms and substrates increased, and separation decreased the microbial activity measured as heat dissipation from the incubation experiment. These results were in line with the expectation from the scale transition theory. In summary, this work provides novel approaches for studying soil C cycling and explicitly highlights a way forward to address two fundamental issues in microbial decomposition—the role of spatial heterogeneities and of energetic constraints on microbial metabolisms.
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| 5. |
- Guasconi, Daniela, 1992-
(författare)
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The hidden half of the meadow : Interactions between drought, soil carbon, roots and soil microbial communities
- 2024
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Soil is a hidden ecosystem which harbours plant roots and countless microorganisms, vital for sustaining life aboveground. These belowground communities provide essential ecosystem services like soil stabilisation and organic matter decomposition. Soil is also one of the largest terrestrial carbon repositories, and land management strategies aimed at increasing organic matter inputs from plants, such as compost additions, can promote further soil carbon accumulation. Because organic carbon is important for soil water retention, this management may also help to increase resilience against more frequent and intense droughts. Although roots and microbial communities are largely acknowledged to play a key role in regulating the carbon cycle, there are still many open questions regarding the link between above- and belowground processes and ecosystem functions. Observing climate- and management-driven changes in the soil habitat is fundamental for understanding how ecosystems respond to environmental change.The aim of this thesis is to explore the relationship between soil properties, plant communities, and soil microbial communities in response to environmental changes. The research builds on a meta-analysis of drought effects on grasslands, and a multifactorial field experiment which combined three years of precipitation reduction and a compost treatment in two Swedish grasslands. We analysed the response of roots and soil microbial communities to drought and compost amendments, and identified environmental factors behind their large spatial variability. Finally, we tested the effects of compost additions on soil carbon storage and its interactions with drought.The results of the meta-analysis indicate that, on a global scale, grassland roots and shoots have diverging responses to drought duration and intensity, with long-term climate mediating that difference. At the local scale assessed in the field experiment, we observed that the spatial patterns of soil microbial communities were driven by soil properties and vegetation. Growing season drought affected roots only at trait level, but did not significantly affect microbial communities. Positive effects of compost on aboveground plant productivity and fungal growth were detectable after three years. Compost amendments also increased the percentage of total soil carbon, but no net increase in soil carbon stocks was detected. Spatial variability in roots and microbial communities was larger than the treatment effects, and was important in shaping microbial community composition and determining grassland responses to drought.Taken together, these findings suggest that roots and microbial communities are likely to be tolerant to drought a within the timescale of this experiment, but we did not observe an increase soil carbon sequestration or drought resilience when adding compost. This thesis highlights the importance of considering soil processes as complementary to aboveground observations when studying carbon dynamics, predicting ecosystem responses to environmental change, and developing sustainable land management practices.
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| 6. |
- Holmes, Felicity Alice, 1995-
(författare)
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Glacier-Ocean Interactions in the Arctic : Contemporary calving and frontal melt from field observations, remote sensing, and numerical modelling
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Globally, glaciers are losing mass as a result of the changing climate, with this mass loss having a considerable societal impact through rising sea levels. Glaciers which terminate in the oceans are particularly vulnerable to changing external conditions as a result of high sensitivity at their marine margins. Both changing meteorological patterns as well as changing ocean heat content and transport have been previously identified as potential drivers for contemporary rapid glacier retreat and acceleration. However, uncertainties remain and provide motivation for studies which improve our process understanding. Here, we use a combination of field data, remotely sensed data, and targeted numerical modelling experiments to investigate marine terminating glacier response to external changes. This is done in order to address uncertainties around mass loss at the inaccessible glacier-ocean interface. In particular, focus is paid to the processes of submarine melt and calving, together referred to as frontal ablation. Submarine melt is the melting of glacier termini by warm ocean waters below the waterline, whilst calving is the breaking off of icebergs from glacier termini. The two processes are interlinked, with submarine melting undercutting the glacier terminus and contributing to calving, whilst calving events can expose larger areas of the glacier margin to submarine melt. To look for relationships between frontal ablation and external forcings, four glacier-fjord systems were studied to varying extents; two grounded glaciers in Svalbard (Kronebreen and Tunabreen) and two glaciers with floating ice tongues in Greenland (Ryder glacier and Petermann glacier). Both submarine melt and calving were examined at various different scales, both temporally and spatially. Specifically, analysis was carried out from the scale of individual calving events up to decadal long time series of glacier margin change. Much of the data used focused on specific glaciological variables such as satellite-derived velocities, margin positions, model simulations, and time-lapse photography of calving events. However, as glaciers and their adjacent fjord or ocean environments impact on each other, data such as water temperatures were also collected from glacier proximal fjord environments. The results from both the observational data and model experiments suggest that ocean temperatures are of great importance for the frontal ablation of glaciers in the Arctic, but that the relationship is complex. Heterogeneous glacier response to external forcings highlights how site specific factors such as bathymetry and fjord geometry can add an additional layer of complexity and make it challenging to scale up results from one glacier to an entire region. However, there are some strong indications that it is the presence of warm air temperatures in conjunction with warm ocean temperatures that is most important for driving frontal ablation - highlighting the need to situate glacier behaviour within a wider environmental context.
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| 7. |
- Kapás, Rozália E., 1988-
(författare)
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Grassland restoration : Connectivity, plant community change and cows
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The ecological significance of semi-natural grasslands is high because these habitats provide a home for a diverse flora and fauna and support a range of associated ecosystem services. Due to large-scale land-use changes the extent of grassland habitat has declined. Hence, restoration efforts to mitigate grassland losses are now being prioritized across the globe and there is an increasing need to understand the drivers behind the recovery of degraded habitats. Since many restoration initiatives rely on spontaneous dispersal of plant species from sources at both local- and landscape-scales, community assembly is influenced by a range of factors which interact both over time and across spatial scales. Given this complexity over the scales, gaps remain in our understanding of how post-restoration management can be designed to facilitate the effective dispersal and establishment of target species in restored grasslands.In this thesis, I examined colonization patterns in Swedish grasslands by comparing plant communities in both ancient and restored grasslands and under contrasting management regimes. At small spatial scales and over the short-term following restoration, I investigated species recruitment sources and their relative contribution to colonization and regeneration. At larger temporal and spatial scales, I examined how the composition of vegetation and seed bank communities is determined by local environmental factors together with distance to species pool and presence of grazing livestock.I found that species mostly colonized spatially from local species sources through seed rain. The seed bank contributed to species colonization to a greater extent in ancient grasslands than in restored grasslands. Management through livestock grazing and shorter distance to species pool were positively associated with the number of species found in grasslands. Grazing livestock facilitated target species establishment into restored sites and the differences between ancient and restored grassland communities were smaller when grazing was active, highlighting that ancient sites can provide a source of colonizing species for restored sites. I found that plant species associated with former land-use declined immediately following restoration, while the occurrence of target species generally increased. However, there was a high initial stochasticity in the establishment of the target species and communities in restored grasslands were still distinct from continuously managed sites even after several decades.These results demonstrate that species presence in nearby ancient grasslands and potential dispersal from the local seed sources drives species colonization in restored and ancient grasslands. Livestock grazing was shown to be an important driver of grassland recovery, either by mediating spatial dispersal of seeds or improving site conditions for establishment. Target species are able to accumulate in the vegetation and seed bank over the long-term, as restored grasslands age. This accumulation will ensure an increasing resilience of grassland communities against future disturbances or changes in the climate. However this depends upon active management, for example by implementing management plans which include continued livestock grazing, and upon conserving remaining ancient grasslands as hotspots for biodiversity within the wider landscape.
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| 8. |
- Katrantsiotis, Christos, 1982-
(författare)
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Holocene environmental changes and climate variability in the Eastern Mediterranean : Multiproxy sediment records from the Peloponnese peninsula, SW Greece
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis presents multiproxy reconstructions of the mid to late Holocene climate and environmental changes in the Peloponnese peninsula, SW Greece. The combined dataset consists of diatom, biomarker and X-ray fluorescence spectrometry (XRF) elemental data in radiocarbon-dated sediment cores taken from the Agios Floros fen and the Gialova Lagoon in SW Peloponnese and the Ancient Lake Lerna in NE Peloponnese. Overall, the results highlight the complex interaction between climate, tectonics and human activities in the landscape development and further reveal changes in the W-E precipitation/temperature gradient over the peninsula connected to shifts in the large-scale atmospheric circulation patterns.The Agios Floros study provides a 6000-year hydrological record based on diatoms and hydrogen isotopic (δD) analysis of aquatic plant-derived n-C23 alkanes. The records indicate two decadal-long periods of deep water conditions at ca 5700 and 5300 cal BP, largely attributed to local tectonic processes and the hydrological anomalies of the nearby karst springs. A period of intermediate water level at ca 4600 cal BP is dominated by the new fossil species Cyclotella paradistinguenda described in this thesis. The gradual development of a fen at ca 4500 cal BP is attributed to a combination of human activities and drier conditions, the latter culminating in SW Peloponnese mainly after ca 4100 cal BP. From ca 2800 cal BP and onwards, there is evidence for flooding events probably related to marked rainfall seasonality.The n-alkane δD profiles and XRF data analyzed in the Gialova core co-vary with each other indicating a common climate signal during the last 3600 years, which resembles the Agios Floros record. The n-alkane δ13C values show high contribution of aquatic vegetation to sedimentary organic matter during wet/cold periods. The n-alkane δD signals from the Lake Lerna also exhibit a similar pattern to each other providing further evidence for precipitation/temperature changes over the last 5000 years.Comparison of the δD records reveals sometimes similar and sometimes opposing signals between NE and SW Peloponnese, which can be attributed to the relative dominance of high latitude and low latitude atmospheric patterns over the peninsula. The records show wet conditions at ca 5000-4600 cal BP likely associated with the weakening of the Hadley circulation. High humidity is also evident at ca 4500-4100, ca 3000-2600 (more unstable in SW) and after ca 700 cal BP with drier conditions at ca 4100-3900 and ca 1000-700 cal BP. These periods correspond to regional climate changes, when the North Atlantic Oscillation (NAO) likely exerted the main control with NAO (+) creating conditions of reduced moisture. A NE-SW climate see-saw with drier conditions in NE Peloponnese is evident at ca 4600-4500, ca 3200, ca 2600-1800 and ca 1200-1000 cal BP and a reversal at ca 3900-3300 ca 3200-3000 and ca 1800-1300 cal BP. The dipole pattern is likely driven by shifts in the North Sea–Caspian Atmospheric pattern (NCP), with NCP (+) leading to wetter and colder conditions in NE Peloponnese. The opposing signal can also be explained by changes in summer temperatures driven by the Asian monsoon intensity. Strong monsoonal periods coincide with cool summers in Lerna, due to the northerly winds (Etesians), in contrast to SW Peloponnese, located on the lee side of the mountain and most affected by the large-scale air subsidence.
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| 9. |
- Ketzer, Daniel, 1988-
(författare)
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Land Use Conflicts between Agriculture and Energy Production : Systems Approaches to Allocate Potentials for Bioenergy and Agrophotovoltaics
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The developments towards a bio-based economy and a renewable energy-based power supply require thorough assessments of feedstocks and frameworks. In the past, political targets for increasing shares of renewable energies for combatting climate change have triggered direct land use changes (LUCs) and even indirect land use changes (iLUCs). As a consequence, residues from grassland and agriculture, which are not used for other purposes, got into the focus of renewable energy policies. Despite the technical feasibility, a general approach for assessing amounts of residues has been lacking, making planning processes for bioenergy highly customized. This study introduces a general, uniform modeling-approach based on Geographic Information Systems (GIS) and publicly available statistical and map data to locate potentials on a 1 km-grid throughout the European Union (EU). Sustainable potentials were calculated for five model regions in Northwest Europe considering input data such as animal livestock, regional (elevation-dependent) yield data, protection areas, and residue-to-crop ratios. Framing two scenarios, the model results were fed into a Decision Support Tool (DST) as a planning tool for bioenergy. Agricultural residues and surplus grass may provide significant potentials on regional levels, e.g. up to 52,236 TJ/ a from straw and 1,301 TJ/ a from root crop residues in Northrhine-Westphalia, or 9,141 TJ/ a from oil plant residues in Île de France, and 12,226 TJ of surplus grass in Rhineland-Palatinate.At the same time, ground mounted PV-systems were installed on arable land formerly used for food or feed production. Hence, high quality soils were taken out of agricultural production. For addressing this type of conflict, Agrophotovoltaic (APV) systems combine agricultural biomass and solar power production on the same site and time for increasing area use efficiency. Even though APV might prove suitable in the technical sense, it might be rejected by society i.e. due to its landscape impact. The Responsible Research and Innovation (RRI)-concept was applied for APV by involving stakeholders already in the technology development process. In a series of workshops with citizens and experts, a comprehensive analysis of the driving and restraining forces for APV was done. A System Dynamics approach with Causal Loop Diagrams (CLD) visualizes and reveals the internal and external dynamics of the APV-technology. Stakeholders have pointed out the importance of defining a good framework for APV first, i.e. roof and industrial areas for PV system shall be exploited first. Any change in the set-up for the PV-system impacts the conditions for the agricultural cultivation conditions, i.e. the height and width of the mounting system influences the working conditions and distribution of water. The shading of the plants can increase the yields in dry and hot summers, while it may lead to yield reductions in other years. The acceptance level is driven by regional aspects such as tourism, local recreation and landscape impact. In this way, local knowledge from participatory studies is seen as prerequisite for a legitimate framework.
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| 10. |
- Larsson, Simon A., 1990-
(författare)
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Ashes to ashes : Applications of tephrochronology in Scandinavia
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The project presented in this thesis provides two examples of applications of tephrochronology in Scandinavia. The usage of tephra deposits preserved in sediments—i.e. horizons of volcanic ashes, detected either as visible layers or as low-concentration “cryptotephras”—is demonstrated to be a strong and versatile tool for chronological control of individual sediment sequences and for correlation between study sites on both local and wider-regional scales.Fieldwork was done at a number of study sites in southernmost Sweden and mid-Norway to sample sediments formed in lakes and peatlands during the Last Glacial–Interglacial Transition, i.e. c. 16,000–8,000 years ago. Labwork was then performed to analyse the sediments by methods to estimate organic matter, organic and carbonate carbon, and elemental contents as well as to find datable macrofossils and to detect tephra occurrences. Among the detected tephras between the different study sites, identifications were made of the Fosen Tephra, the Hässeldalen Tephra, the Vedde Ash, and the Laacher See Tephra. These were used for the purposes of either application in the project; (1) a palaeoclimate reconstruction at Körslättamossen, with new proxy analyses and correlations to a previous study of the same site as well as to other studies in Europe via linkages established by the tephras, and (2) a palaeoglaciological reconstruction on the Fosen peninsula, based on correlations between study sites using the detected tephras to assess the timing of glacial retreat in the area.The palaeoclimate reconstruction at Körslättamossen and correlation to previous studies provides new information about the climatic development in Europe after the end of the last ice age, specifically regarding the timing of the cold stage known as the Younger Dryas. Detailed knowledge of such events, spatially and temporally, is necessary to understand the behaviour of the climate system in the past and, thereby, its behaviour in the present and the future. This is one of several studies demonstrating the usefulness of tephrochronology for such research questions.The palaeoglaciological reconstruction on the Fosen peninsula, also relating to the Younger Dryas, is one of a few recent studies which demonstrate the strengths of tephra investigations in providing evidence for the timing of events on more local scales than the wider spatial perspective more often utilised in tephrochronological applications. Other than resulting in a significantly revised chronology for the retreat of the Scandinavian Ice Sheet in the study area, this study should also encourage new, similar tephra studies in future Quaternary research.In addition to the direct results of either study (mainly presented in the related scientific papers) and the addition of new reference data for later tephra studies, the thesis also discusses further implications of the results and observations made with emphasis on considerations and study design issues in Quaternary research at large and for the tephrochronologist in particular.
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